Mowing methods

ABSTRACT

A mower includes a plurality of cutting heads, each cutting head having a minor cutting width, the plurality of cutting heads connected by a plurality of connectors in an array having a variable major cutting width. The mower also includes a steering system coupled with a first driven wheel and supported by one cutting head, and a second driven wheel supported by one other cutting head. The steering system is capable of steering the first driven wheel independently from the second driven wheel.

RELATED APPLICATIONS

This application claims priority from U.S. Non-Provisional patentapplication Ser. No. 14/884,617, filed Oct. 15, 2015, which claimspriority from U.S. Provisional Patent Application No. 62/100,835, filedJan. 7, 2015. The entire contents of both applications are herebyincorporated by reference.

BACKGROUND

The invention relates to mowers having a plurality of cutting heads forcutting large areas of grass.

SUMMARY

Mowers cut grass in a wide variety of applications, ranging in size fromresidential lots, to athletic fields, to expansive turf farms. Formowers known in the art, cutting rate is generally calculated as forwardspeed multiplied by cutting width. Therefore, the cutting rate of amower known in the art increases linearly as either the cutting width orforward speed increases, all else equal. This linear relationship limitsproductivity and efficiency gains deliverable by large mowers known inthe art. It would therefore advance the art to provide a mower and amethod of use whereby cutting rate is not constrained by a linearrelationship to the cutting width.

Mowers with wide cutting widths face access problems. That is, a mowercan generally only traverse openings wider than its widest point. Thislimitation can force users to use a narrower mower than would otherwisemore efficiently handle a job. For example, some lots are accessibleonly through gates; in the residential context, this can effectivelyprohibit the use of mowers wider than 30-36 inches when wider equipmentwould otherwise mow the lot in less time. To alleviate this problem,certain large mowers feature retractable cutting decks (e.g., bat wingconfigurations), to the detriment of expense and complexity. Forresidential and smaller commercial applications however, mowers withcutting widths less than 72 inches generally lack the capability toovercome this challenge. It would therefore advance the art to provide amower capable of traversing passageways much narrower than its cuttingwidth.

In addition to the aforementioned shortcomings, large commercial mowersface mobility problems between job sites. For example, trailer size canlimit a user's choice of equipment even if larger mowers would otherwisemeet the user's needs more efficiently. It would therefore advance theart to provide a mower capable of altering its dimensions, so that itoffers a higher cutting rate relative to its footprint.

With few exceptions, the cutting widths of mowers known in the art arefixed. This is undesirable because it limits a mower's applications. Italso requires the user to choose between investing in different mowersizes for different applications, using non-optimally sized equipmentfor certain jobs, or forgoing certain jobs entirely. To enable users toutilize one piece of equipment for numerous job sizes, it would advancethe art to provide a mower with an adjustable cutting width.

In summary, it would advance the mower art to provide a mower and amethod of use whereby cutting rate is not constrained by a linearrelationship to the cutting width, wherein the mower has an adjustablecutting width, greater accessibility and mobility relative to itscutting rate.

Accordingly, the invention provides, in one aspect, a mower. The mowerincludes a plurality of cutting heads, each cutting head having a minorcutting width, the plurality of cutting heads connected by a pluralityof connectors in an array having a variable major cutting width, whichcan be measured along a major cutting width axis. The mower alsoincludes a steering system coupled with a first driven wheel andsupported by one cutting head, and a second driven wheel supported byone other cutting head. The steering system is capable of steering thefirst driven wheel independently from the second driven wheel.

In another aspect, the invention provides a mower having at least oneconnector translatably joining at least one cutting head to at least oneother cutting head. At least one connector may pivotably join at leastone cutting head to at least one other cutting head. At least oneconnector may have a first retainer connected to a second retainer. Thefirst retainer may translatably receive at least one cutting head, andthe second retainer may translatably receive at least one other cuttingheads.

In another aspect, the invention provides a mower having at least threecutting heads. In another aspect, the minor cutting width of at leastone cutting head is between twenty and seventy-two inches, inclusive. Inanother aspect, the minor cutting width of at least one cutting head isat least seventy-two inches. In another aspect, the maximum majorcutting width of the mower is at least one hundred inches. In anotheraspect, the mower has a transport width less than seventy-two inches.

In another aspect, the invention provides a method for using a mower,the mower including a plurality of cutting heads connected by aplurality of connectors in an array having a variable major cuttingwidth. The mower has a first steering system coupled with a first drivenwheel and supported by one cutting head, and a second steering systemcoupled with a second driven wheel and supported by one other cuttinghead.

In one aspect, the invention provides a method for using a mower asdescribed above, the method including the steps of steering the firstdriven wheel and driving the first driven wheel. In another aspect, themethod includes the additional steps of steering the second driven wheeland driving the second driven wheel. When the steps of the method areperformed, the mower achieves a cutting rate proportional to the squareof the major cutting width, wherein the cutting rate can be modeled byan equitation having an exponential component, such as C=(1−k)zπr²,where C corresponds to cutting rate, k corresponds to a loss factor, zcorresponds to a rotational rate, and r corresponds to the major cuttingwidth.

In another aspect, the method includes steering the first driven wheeland second driven wheel so that their respective directions of travelare approximately perpendicular to the major cutting width axis. Thefirst driven wheel may be driven for a period of time sufficiently longto cause the mower to pivot at least approximately one hundred eightydegrees about the second driven wheel. Before or after driving firstdriven wheel, the second driven wheel may be driven for a period of timesufficiently long to cause the mower to pivot at least approximately onehundred eighty degrees about the first driven wheel.

In another aspect, the invention provides a method for varying the majorcutting width of the mower, wherein the first driven wheel is steered sothat its direction of travel is approximately parallel to the majorcutting width axis and driven in a direction approximately parallel tothe major cutting width axis. Additionally, the second driven wheel maybe steered so that its direction of travel is approximately parallel tothe major cutting width axis and driven in a direction approximatelyparallel to the major cutting width axis. When performing such a method,the first driven wheel and second driven wheel may be drivensimultaneously or sequentially.

In another aspect, the invention provides a method for varying themaximum major cutting width of a mower having a plurality of cuttingheads connected in an array by a plurality of connectors, a first drivenwheel supported by one cutting head of the plurality of cutting heads, asecond driven wheel supported by one other cutting head of the pluralityof cutting heads, and a steering system for steering the first drivenwheel independently from the second driven wheel. The method includesthe steps of disconnecting a first cutting head from a second cuttinghead, inserting an intermediate cutting head between the first cuttinghead and the second cutting head, connecting the first cutting head tothe intermediate cutting head, and connecting the second cutting head tothe intermediate cutting head. In another aspect, connectors may be usedto connect the first cutting head and second cutting head to theintermediate cutting head.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a front perspective view of a mower in an extendedposition according to one embodiment of the invention.

FIG. 1B shows a front perspective view of a mower in a collapsedposition according to one embodiment of the invention.

FIG. 1C shows a rear perspective view of a mower in a collapsed positionaccording to one embodiment of the invention.

FIG. 2A shows a top schematic view of a mower in an extended positionaccording to one embodiment of the invention.

FIG. 2B shows a top schematic view of a mower in a collapsed positionaccording to one embodiment of the invention.

FIG. 3A shows a front schematic view of a mower in an unarticulatedposition according to one embodiment of the invention.

FIG. 3B shows a front schematic view of a mower in an articulatedposition according to one embodiment of the invention.

FIG. 3C shows a front schematic view of a mower in another articulatedposition according to one embodiment of the invention.

FIG. 4A shows a front perspective view of one cutting head according toone embodiment of the invention.

FIG. 4B shows a rear perspective view of one cutting head according toone embodiment of the invention.

FIG. 4C shows a front view of one cutting head according to oneembodiment of the invention.

FIG. 4D shows a top view of one cutting head according to one embodimentof the invention.

FIG. 4E shows a bottom view of one cutting head according to oneembodiment of the invention.

FIG. 4F shows a close up view of a geartrain and cutting blade of onecutting head according to one embodiment of the invention, with acutting reel removed.

FIG. 5A shows a top schematic view of an alternative cutting head with asingle cutting reel and two cutting blades.

FIG. 5B shows a side schematic view of an alternative cutting head witha single cutting reel and two cutting blades.

FIG. 6A shows a top schematic view of another alternative cutting headwith rotary cutting blades.

FIG. 6B shows a side schematic view of another alternative cutting headwith rotary cutting blades.

FIG. 6C shows a top schematic view of another alternative cutting headwith flexible cutting line.

FIG. 6D shows a side schematic view of another alternative cutting headwith flexible cutting line.

FIG. 7 shows a connector adjoining two cutting heads according to oneembodiment of the invention.

FIG. 8A shows a top view of the connector of FIG. 7.

FIG. 8B shows a front view of the connector of FIG. 7

FIG. 8C shows a side view of the connector of FIG. 7, emphasizing theability to articulate.

FIG. 9A shows a front perspective view of a driven wheel and steeringsystem according to one embodiment of the invention.

FIG. 9B shows a rear perspective view of a driven wheel and steeringsystem according to one embodiment of the invention.

FIG. 10 schematically shows a rotational cutting method according to oneembodiment of the invention.

FIG. 11A schematically shows a cutting pattern made possible by a moweraccording to one embodiment of the invention.

FIG. 11B schematically shows another cutting pattern made possible by amower according to one embodiment of the invention.

FIG. 12 shows a translational method according to one embodiment of theinvention.

FIG. 13 shows a modular adjustment method according to one embodiment ofthe invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced invarious ways. As used in this application to modify values orrelationships, the word “approximately” means “within ten percent.”

With reference to FIGS. 1A-3C, a mower 10 includes a modular array ofconnected cutting heads 20, including two outer-most cutting heads andoptionally one or more intermediate cutting heads. Each cutting head 20has a minor cutting width, generally defined as the width of a strip ofgrass the cutting head 20 could cut. For example, the minor cuttingwidth may reflect the width of a cutting reel 30 supported by cuttinghead 20, or alternatively by the sum of the widths of a plurality ofcutting reels 30 or cutting blades supported by cutting head 20.Embodiments constructed for applications without space constraints mayfeature large minor cutting widths, e.g., at least seventy-two inches,whereas embodiments constructed for applications with space constraints(e.g., applications constrained by trailer are access dimensions) mayfeature smaller minor cutting widths, e.g., between twenty andseventy-two inches, inclusive. Connectors 40 between each cutting head20 enable relative translation (as shown by comparing FIGS. 1A and 1B)and pivoting (as shown in FIGS. 3A-3C). Mower 10 has a variable majorcutting width corresponding to a major cutting width axis 32, and equalto the sum of the minor cutting widths of cutting heads 20, less anyoverlap between cutting heads 20. A small amount of overlap betweencutting heads 20 is ideal in order to prevent “streaking,” or strips ofuncut grass between cutting heads. Accordingly, when the overlap betweencutting heads 20 is relatively small, as shown in FIG. 1A and 2A, themajor cutting width can be quite large. On the other hand, when thecutting heads 20 overlap entirely as shown in FIGS. 1B and 2B, the majorcutting width is approximately equal to the width of a single cuttinghead 20. Embodiments constructed for applications without spaceconstraints may feature large maximum major cutting widths, e.g., atleast one hundred inches, whereas embodiments constructed forapplications with space constraints may feature maximum major cuttingwidths less than one hundred inches. Referring to FIG. 2B, the mower 10may be further characterized by its transport width, which is theminimum width of mower 10 measured along the transport width axis 34.Embodiments constructed for applications with space constraints mayfeature smaller transport widths, e.g., less than seventy-two inches.

Each cutting head 20 includes at least one wheel 50. Additionally, eachouter-most cutting head 20 includes a driven wheel 52 that is ideallysteerable. An internal combustion engine, battery, solar panel, or otheron-board power source 60 may power mower 10; alternatively, mower 10 maydraw power from a remote source, such as an electric grid or generator,or may be human-powered. An operator may control mower 10 by hydraulic,pneumatic, or electrical means, as known in the art. Hydraulic,pneumatic, and/or electrical connections between components are known inthe art and presumed to function.

In operation, by performing a rotational cutting method, describedbelow, mower 10 can cut grass in a novel end-over-end manner as shown inFIG. 10. The cutting rate of the mower 10 while performing therotational cutting method is proportional to the square of the majorcutting width. Intuitively, as the major cutting width and therotational rate increase, mower 10 can achieve very large cuttingcapacities. Additionally, the rotational cutting method enables mowingpatterns not easily achievable by mowers known in the art, includingcircular and scalloped patterns as illustrated in FIGS. 11A and 11B.

In addition to mowing in an end-over-end manner, mower 10 can cut grassin a linear manner by performing a translation method described below,which also enables it to traverse openings narrower than its majorcutting width. By performing a width adjustment method, described below,mower 10 may assume an extended arrangement with a maximum major cuttingwidth, a compact arrangement with a minimum major cutting width, andmany intermediate arrangements. In the extended arrangement shown inFIGS. 1A and 2A, cutting heads 20 are positioned with minimal overlap tomaximize the major cutting width. In the compact arrangement, cuttingheads 20 are positioned with maximum overlap to minimize the majorcutting width and to consolidate the footprint of the mower 10 (e.g., tofacilitate transportation). By performing a modular adjustment method,described below, the user can add or remove cutting heads 20 to increaseor decrease the maximum major cutting width, respectively. Altogether,mower 10 and its methods of use enable a user to cut grass efficiently,adjust the major cutting width for specific jobs and transportationrequirements, traverse narrow passages, and create circular, scalloped,and other nonlinear mowing patterns.

The mower 10 has a modular construction to facilitate increases orreductions to the major cutting width. That is, the user may attachadditional cutting heads 20 to mower 10 in order to increase its overallcutting rate. Likewise, the user may remove cutting heads 20, forexample to accommodate the requirements of a particular job, or tointerchangeably use a cutting head 20 on another mower 10 builtaccording to the present invention. To enable this modularity, cuttingheads 20 may feature common dimensions and structure such as connector40 described below, along with quick release hydraulic and/or electricalconnections.

With reference to FIGS. 4A-4F, each cutting head 20 includes an elongateframe 70 that supports at least one cutting reel 30 and at least onecutting blade 90. Additionally, frame 70 may support other components,including wheels 50, and hydraulic and/or electrical equipment. In theillustrated embodiment, frame 70 includes two end plates 100 connectedto opposing ends of frame elements 110. End plates 100 may beconstructed from metal (e.g., stamped steel or aluminum), injectionmolded plastic, or other rigid material. End plates 100 support the endsof frame elements 110, such as by receiving them through apertures 120.In the illustrated embodiment, apertures 120 are positioned toward theperimeter of end plates 100 to increase the internal space bounded byframe elements 110. Alternatively, frame elements 110 could be arrangedin a vertically-biased configuration, such as to increase cutting head's20 resistance to bending, or in another configuration. It is generallydesirable to increase each cutting head's 20 resistance to bending(e.g., bending caused by the weight supported by the frame 70). Weldingeach frame element 110 to each corresponding end plate 100 can improveresistance to bending. However, other permanent or temporary joiningmethods may be used to affix the positions of the end plates 100 towardthe ends of frame elements 110, including but not limited to frictionfitting, clamping, fastening, and threading. Regardless of the joiningmethod, the position of each end plate 100 should be at leasttemporarily fixed with respect to the length of each frame element 110.

The embodiment of cutting head 20 illustrated in FIGS. 4A-4F includesfour frame elements 110 and two end plates 100. Each frame element 110has a single finite length, although each frame element 110 couldalternatively include an assembly of sub elements, for example subelements axially connected by threading, welding, or other joiningmethod. Additional or fewer frame elements 110 may be desirable toincrease the strength of cutting head 20 or to reduce weight and cost,respectively. In the illustrated embodiment, the cross section of frameelements 110 is cylindrical, but may alternatively be polygonal, anynumber of structural shapes such as symmetrical I-shapes, asymmetricalI-shapes, wide flange I-shapes, S-shapes, Z-shapes, C-shapes,Tee-shapes, hollow structural sections, single angle sections, anddouble angle sections, or reflect another shape. As noted above, it isdesirable to increase each cutting head's 20 resistance to bending, theobjective being to ensure an approximately uniform distance between theground along the length of cutting blade 90. With the realization thatbending cannot be entirely eliminated, it may be desirable for eachframe element 110 to exhibit some preloaded deflection relative to itselongate axis in order to counteract deflection resulting from weightsupported by frame 70. It is envisioned that frame elements 110 will beconstructed of aluminum, steel, or other metal, but could instead bemanufactured from other materials, such as but not limited to plastic ororganic material. Frame elements 110 may support a protective cover(e.g., a deck, fairing, shroud, not shown in the illustrated embodiment)to enhance safety. A cover that prevents debris from escaping fromcutting head 20 may be important for those embodiments that supportrotary cutting assemblies, as described below.

The cutting head 20 illustrated in FIGS. 4A-4F includes two cuttingreels 30 a, 30 b, the construction of which are known in the art. Endplates 100 support a first cutting reel 30 a approximately parallel to asecond cutting reel 30 b, each cutting reel 30 a, 30 b having two endsand approximately equal lengths that define the minor cutting width.Each cutting reel 30 a, 30 b may be constructed as a single reel oralternatively may include an end-to-end assembly of two or more smallerreels. Frame 70 supports each end of cutting reels 30 a, 30 b in ahorizontal orientation with respect to the ground. For example, reelapertures 130 in each end plate could contain reel bearings that supporteach end of cutting reels 30 a, 30 b. A hydraulic reel motor 140 rotatesfirst reel 30 a about its longitudinal axis. Reel motor 140 couldalternatively be electrically-powered. In the illustrated embodiment, ageartrain 150 connecting the first and second reels 30 a, 30 b causessecond reel 30 b to rotate about its longitudinal axis in the oppositedirection from first reel 30 a.

End plates 100 support cutting blade 90 in between and approximatelyparallel to cutting reels 30 a, 30 b. Cutting blade 90 has a lengthapproximately equal to the total length of cutting head 20. Frame 70supports blade 90 so that its first and second edges are approximatelytangential to the circumferences of cutting reels 30 a, 30 b,respectively. To ensure cutting blade 90 maintains a uniform distancefrom the ground, it may be desirable include an additional support atone or more intermediate points along its length. For example, twocantilevered supports projecting perpendicularly from each end plate 100may affix to either end of cutting blade 90. In operation, reel motor140 causes cutting reels 30 a, 30 b to rotate counter to each other. Thereel blades of cutting reels 30 a, 30 b capture grass and sweep itagainst the edges of blade 90, thereby cutting the grass.

An alternative cutting head 170, illustrated in FIGS. 5A-5B, supportsone cutting reel 182, a first cutting blade 180 a, and a second cuttingblade 180 b. Each cutting blade 180 a, 180 b is positioned parallel andadjacent to opposite sides of cutting reel 182, with the edge sidefacing cutting reel 182. Frame 70 supports blades 180 a, 180 b so thatthe edges are approximately tangential to the circumference of the reel182. A bidirectional hydraulic or electric reel motor 190 drives cuttingreel 182 in an overhand motion toward the direction of travel of mower10. When mower 10 is operated according to the rotational cutting methoddescribed below, reel motor 190 reverses direction as mower 10 moves endover end to rotate cutting reel 182 in the direction of travel. As mower10 moves, motor 190 causes cutting reel 182 to sweep grass against oneblade 180; when mower 10 changes directions, motor 190 reverses, andreel 182 sweeps grass against the other blade 180.

Another alternative cutting head 200 is illustrated in FIGS. 6A-6D. Theframe elements 110 support a plurality of rotary cutting assemblies,each rotary assembly including a horizontal cutting blade 210 attachedto a vertical spindle 220. Flexible cutting line 230 may substitute forfixed cutting blades 210, as shown in FIGS. 6C-6D. Regardless of whetherblades 210 or cutting lines 230 are used, each rotary cutting assemblyis suspended from a horizontal platform or struts that span the frameelements 110. A motor drives each spindle 220 about its vertical axiseither directly (e.g., a hydraulic or electric motor is affixed to eachspindle 220) or indirectly (e.g., power from a single motor istransferred to each spindle 220 on the same cutting head via a belt andpulley, geartrain, or hydraulic means). This arrangement could offeradvantages in terms of balancing and serviceability. Given the largerotating masses in such a configuration, it may be desirable to coverframe 70 with a shroud or fairing to protect the user from debris.

With reference to the mower 10 in FIGS. 1A-3C, each cutting head 20pivotally and slidably attaches to each adjacent cutting head by aconnector 40. With reference to FIGS. 7, 8A-8C, an illustratedembodiment of connector 40 includes a first and a second retainer 240 a,240 b, each having a primary aperture 250 a, 250 b extendingtherethrough and approximately reflecting the cross section of frameelements 110. Retainers 240 a, 240 b also include a secondary aperture260 a, 260 b, respectively, that receives a capture mechanism 270, whichcouples retainers 240 a, 240 b together and enables relative rotation,e.g., as a result of terrain changes (as shown in FIGS. 3A-3C). In theillustrated embodiment, capture mechanism 270 comprises a bolt, washer,and nut assembly. In operation, each primary aperture 250 a, 250 breceives a frame element 110 of an adjacent cutting head 20 in aconnected configuration. In the connected configuration, each frameelement 110 may translate relative to connector 40 as frame elements 110slide through primary apertures 250 a, 250 b. By extension, connector 40also enables cutting heads 20 to translate relative to one another, suchas during the width adjustment method described below or transitionsbetween the extended arrangement and compact arrangement. To facilitatemovement, connector 40 may include grease zerks for lubrication,bearings fitted into the retainers, and/or additional structure toreduce the friction between frame elements 110 and the connector 40.Each retainer 240 a, 240 b may further include a first part 280 a thatremovably mates to a second part 280 b, thereby enabling selectiveremoval and attachment of connector 40 from cutting head 20; thisfunctionality is useful for the modular adjustment method describedbelow. In addition to enabling cutting heads 20 to translate and pivotrelative to one another, connector 40 enables the user to modularlyincrease or decrease the major cutting width of mower 10 by adding orremoving cutting heads 20, such as by performing the modular adjustmentmethod described below.

Mower 10 rides upon wheels 50 and driven wheels 52, which may be affixedto cutting heads 20 (e.g., affixed to end plates 100) or mounted uponseparate carriages. Caster wheels are well suited to the methods of usemore fully developed below. Each cutting head 20 in the embodimentillustrated in FIGS. 1A-3C includes at least one caster wheel 50 affixedto an end plate 100. Additionally, each outermost cutting head 20includes a driven wheel 52 affixed to an end plate 100. Additionalwheels 50 mounted between end plates 100 (e.g., mounted on one or moreframe elements 110) could facilitate the mower's 10 movement by reducingground pressure and by preventing “high-siding.” In the illustratedembodiment of a driven wheel 52 in FIGS. 9A-9B, each driven wheel 52includes a mounting plate 290 affixed to a caster arm 300, which isaffixed to a yoke collar 310. Yoke collar 310 slidably receives a wheelyoke 330, which is connected to a fork 340, a rim 350, a tire 360, a hub370, and height adjustment spacers 380. By this arrangement, wheel 50may rotate about the vertical axis of wheel yoke 330. The user canselectively adjust the cutting height by placing height adjustmentspacers 380 below caster arm 300 (to increase cutting height) or abovecaster arm 300 (to decrease cutting height).

While it is possible for mower 10 to include all passive, non-propelledwheels 50, the inclusion of driven wheels 52 may enable it to achievecommercially-attractive capabilities, including higher cuttingcapacities, safer operation, and easier transportation. Ideally, drivenwheels 52 are capable of reversing the driven direction. Additionally,it is advantageous for driven wheels 52 to be steerable. Equipping mower10 with a steerable, driven wheel 52 at each outer-most cutting head 20enables a high degree of maneuverability and efficiency.

The embodiment of mower 10 illustrated in FIGS. 1A-3C includes drivenwheels 52 a, 52 e of the type illustrated in FIGS. 9A-9B, one connectedto each outer-most cutting head 20 a, 20 e, respectively. Each drivenwheel 52 includes a bi-directional hydraulic wheel motor 390 that drivescorresponding driven wheel 52 about its hub axis. Alternatively, wheelmotor 390 could be electric, and a geartrain could reside between thewheel motor and the wheel hub in order to increase mechanical advantage.Each driven wheel 52 features a steering system 400, including a rack410 and a pinion 420 to move driven wheel 52 about its vertical yokeaxis. A hydraulic actuator 430 is fastened to caster arm 300, such aswith bolts and nuts, and connects to rack 410. Actuator 430 or connectedtubing and/or wiring may include a pressure relief valve that enableswheel yoke 330 to rotate about its axis with less resistance. Pinion 420mates with yoke 330 at a height so that the teeth of pinion 420 engagethe teeth of rack 410. A spline joint may couple the rotation of yoke330 and pinion 420, while preserving the relationship between pinion 420and rack 410 as the user adjusts the cutting height by selectivelyplacing height adjustment spacers 380 above or below caster arm 300. Inoperation, as actuator 430 drives rack 410 outward, its teeth engagepinion 420, causing yoke 330 to rotate about its axis. Also, whenactuator 430 stops, it may hold yoke 330 in a fixed position withrespect to its axis unless the pressure relief valve is actuated. Bythis structure, the user can precisely steer driven wheel 52. Anelectric actuator and electric motor could replace actuator 430 andhydraulic wheel motor 390, respectively. Furthermore, numerous forms ofgearing could induce wheel yoke 330 to rotate about its vertical axisinstead of a rack and pinion arrangement. For example, a worm driven bya motor with a horizontal shaft could engage a worm gear mounted alongthe wheel yoke, or a bevel gear driven by a motor with a horizontalshaft could engage another bevel gear mounted along the wheel yoke, or apinion gear driven by a motor with vertical shaft could engage anotherpinion gear mounted along wheel yoke 330.

To power reel motors 140, rotary motors 190, wheel motors 390, andactuators 430, the mower 10 may support its own power source 60, whichmay include an internal combustion engine, a battery, a solar panelarray, a fuel cell, or other source. For applications where electricityis available, mower 10 may be configured to draw power from anelectrical grid, e.g., via a cord. Depending on whether the motors arehydraulic or electric, embodiments equipped with an internal combustionengine may include a hydraulic system (e.g., including a hydraulic pump,fluid reservoir, and throttling valves), an electrical system (e.g.,including a magneto or alternator), a pneumatic system (e.g., includinga compressor and air tank), or a combination of two or more systems. Thetubing, wiring, piping, and other structure inherent to such systems isknown in the art and assumed to operatively integrate with power source60, reel and/or rotary motors 140, 190, wheel motors 390, and actuators430.

The user may control mower 10 by direct and remote methods known in theart. It is envisioned mower 10 will feature a remote control systemcomprising a controller to accept user inputs (e.g., steering angle,driven wheel speed, cutting reels on/off) and transmit signalscorresponding to those inputs, and a receiver and a processor located onthe mower to receive and manipulate the signals, respectively. The mowermay also include sensors to record signals corresponding to usefulparameters, e.g., fuel level, engine coolant temperature, engine RPM,cutting reels on/off, and ground speed. In such embodiments, the mower10 will utilize a transmitter or a transceiver to transmit thisinformation back to the controller. The controller and receiver maycommunicate directly (e.g., through RF) or indirectly (e.g., through GPSor cellular infrastructure). Alternatively, the user may manipulatemower 10 via a controller tethered via an umbilical connection that mayinclude electrical wiring and hydraulic lines. Regardless of the controlsystem selected, the controlling methods are known in the art andpresumed to operatively control the individual components and overallsystem of the present invention.

In operation, the user performs a rotational cutting method to causemower 10 to mow grass in an end-over-end motion as illustrated in FIG.10. For example, with reference to FIGS. 1A-3C, 9A-9B, the usermanipulates first and second driven wheels 52 a, 52 e corresponding tothe outermost cutting heads 20 a and 20 e, respectively. To perform therotational cutting method, the user first actuates actuator 430 ofsteering system 400 of cutting head 20 a, causing the attached rack 410to translate, and the enmeshed pinion 420 and yoke 330 to rotate aboutthe vertical yoke axis until the hub axis of the first driven wheel 52 abecomes approximately parallel to the major cutting width axis 32. Inother words, the user steers first driven wheel 52 a until its directionof travel is approximately perpendicular to the major cutting width axis32. Second, with cutting reels 30 rotating, the user actuates wheelmotor 390 of first driven wheel 52 a for a period of time, causing mower10 to pivot about second driven wheel 52 e. After causing mower 10 topivot about second driven wheel 52 e by a desired degree (e.g., 180 or540 degrees), the user then executes the third step by actuatingactuator 430 of steering system 400 of second driven wheel 52 e, causingthe attached rack 410 to translate, and the enmeshed pinion 410 and yoke330 to rotate about the vertical yoke axis until the hub axis of secondwheel 52 e becomes approximately parallel to the major cutting widthaxis 32. Fourth, the user actuates wheel motor 390 of second drivenwheel 52 e fora period of time, causing mower 10 to pivot in the samedirection as in step two about first driven wheel 52 a (e.g., by 180 or540 degrees). By repeatedly executing the first through fourth steps,the user can cause mower 10 to mow grass while moving in an end-over-endmotion. The method is effective for both clockwise and counterclockwisemotion. In practice, if the user causes mower 10 to pivot in a clockwisedirection by 180 degrees about second driven wheel 52 e (steps one andtwo), and then in a clockwise direction by 180 degrees about firstdriven wheel 52 a (steps three and four), mower 10 will advance in alinear direction while covering semicircular areas of ground.Alternatively, if the user causes mower 10 to pivot by 540 degrees aboutsecond driven wheel 52 e, and then 540 degrees about first driven wheel52 a, mower 10 will advance in a linear direction while coveringcircular areas of ground, as illustrated in FIGS. 11A-11B. Because mower10 covers circular areas of ground, the covered area is proportional tothe square of the major cutting width. Separately, the total area thatmower 10 can cover is proportional to the rotational velocity with whichit pivots about driven wheels 52 a, 52 e. Thus, by using theaforementioned rotational cutting method to operate mower 10 with alarge major cutting width and high rotational velocity, the user can mowvery large areas of grass in short time periods. The cutting rate of themower while performing the rotational cutting method can be modeled bythe following equation.

C=(1−k)zπr ²

where:

C=cutting rate (e.g., square feet per hour)

k=loss factor attributable to overlap between passes (dimensionless)

z=rotational rate (e.g., rotations per hour)

r=major cutting width (e.g., feet)

To cause mower 10 to increase or decrease its major cutting width, theuser performs a width adjustment method by first actuating actuators 430of the first and second steering systems 400 corresponding to cuttingheads 20 a, 20 e, causing the connected racks 410 to translate until thehub axes of driven wheels 52 a, 52 e become approximately parallel toeach other and perpendicular to the major cutting width axis 32. Inother words, the user steers driven wheels 52 a, 52 e so that thedirection of travel of each is parallel to the major cutting width axis32. With driven wheels 52 a, 52 e pointing in the same direction andparallel to major cutting width axis 32, the user actuates wheel motors390 in opposite directions, thereby causing driven wheels 52 a, 52 e todrive away from each other (thereby causing the major cutting width toincrease until it reaches the maximum major cutting width) or inwardlyin opposite directions (thereby causing the major cutting width todecrease until it reaches the minimum major cutting width). Duringeither of these operations, cutting heads 20 translate relative to oneanother along their longitudinal axes by virtue of connectors 40. Theuser may actuate wheel motors 390 simultaneously or in sequentially.Instead of manipulating both driven wheels 52 a, 52 e, the user mayalternatively increase or decrease the major cutting width by steeringeither driven wheel 52 a or 52 e in a direction parallel to the majorcutting width axis 32, and then actuating that wheel 52 as necessary.

To cause mower 10 to move linearly, the user performs a translationmethod by first actuating actuators 430 of first and second steeringsystems 400 corresponding to cutting heads 20 a, 20 e, causing theconnected racks 410 to translate until the hub axes of driven wheels 52a, 52 e are approximately parallel to each other. Second, the useractuates wheel motors 390 of driven wheels 52 a, 52 e in the samedirection, thereby causing mower 10 to move in the direction of travelof driven wheels 52 a, 52 e. By executing this method, mower 10 can cutswaths of grass as wide as its major cutting width while movinglinearly. On the other hand, by executing this method when the hub axesof driven wheels 52 a, 52 e are pointed in a direction approximatelyperpendicular to the major cutting width axis 32, mower 10 can proceedthrough openings narrower than its major cutting width, as illustratedin FIG. 12.

To increase the maximum major cutting width of mower 10, the userperforms a modular adjustment method, illustrated in FIG. 13. The useraccomplishes this by inserting or removing one or more intermediatecutting heads 20 to mower 10. To add an additional cutting head (e.g.,cutting head 20 f), the user first disconnects a first cutting head(e.g., cutting head 20 d) from an adjacent cutting head (e.g., cuttinghead 20 e) by disconnecting the adjoining connector (e.g., connector 40e). Next, the user connects an additional cutting head (e.g., cuttinghead 20 f) to first cutting head 20 d via connector 40 f. Finally, theuser connects cutting head 20 f to cutting head 20 e via connector 40 e.

Thus, from the foregoing discussion the reader will see that at leastone embodiment of the invention is unique as a modular assembly ofslidably connected cutting heads 20 capable of performing a novelmaneuvers that enhance productivity and create novel mowing patterns.For example, with driven wheels 52 a, 52 e positioned at opposite endsof mower 10, it is capable of performing an end-over-end cutting motion(thereby linking the cutting rate to the square of its major cuttingwidth) and traversing passages narrower than its major cutting width,unlike mowers known in the art. Nevertheless, additional drive wheelscould prove advantageous, such as to facilitate movement acrosslow-traction terrain. Indeed, when each wheel has full rotationalcapability about its vertical yoke axis, there are many more possibleintermediate positions and maneuvers. When the direction of travel of adriven wheel 52 is changed as wheel motor 390 drives the wheel,additional maneuvers are possible. For example, the user can execute anend-over-end maneuver with a continuously decreasing major cutting widthby steering one driven wheel 52 to an acute angle with respect to themajor cutting width axis 32 as a drive wheel 52 propels one end of mower10. Additionally, the user can move mower 10 in a linear manner whilecontinuously increasing or decreasing the major cutting width byexecuting the linear movement described above, with one driven wheel 52steering at an obtuse angle with respect to cutting head 20 (therebycausing the major cutting width to increase as the mower 10 movesforward) or an acute angle with respect to cutting head 20 (therebycausing the major cutting width to decrease as mower 10 moves forward).These additional maneuvers could be useful for mowing regions withirregular dimensions, as are commonly encountered in the industry.Accordingly, the scope should be determined by the appended claims andthe legal equivalents thereof, not by the illustrated embodiments.

Thus, the invention provides a mower comprising a variable, connectedarray of cutting heads capable of achieving high cutting capacities andof performing a novel rotational cutting method, while also alleviatingknown mobility and access problems associated with mowers known in theart. Various features of the invention are set forth in the followingclaims.

I claim:
 1. A method for using a mower, comprising: providing a mowercomprising a frame having a length corresponding to a longest dimensionof the mower, a first driven wheel that is supported near a first end ofthe length, and a second driven wheel that is supported near a secondend of the length; driving the first driven wheel such that the mowerrotates about the second end.
 2. The method of claim 1, wherein themower moves across an area that is proportional to the square of alength of the mower.
 3. The method of claim 1, wherein the step ofdriving the first driven wheel occurs while the second driven wheel isnot driven.
 4. The method of claim 1, further comprising a step ofdriving the second driven wheel such that the mower rotates about thefirst end.
 5. The method of claim 4, wherein the step of driving thesecond driven wheel occurs after the step of driving the first drivenwheel.
 6. The method of claim 5, wherein the steps of driving the firstdriven wheel and driving the second driven wheel occur while the moweris cutting grass.
 7. The method of claim 1, wherein the step of drivingthe first driven wheel comprises driving the first driven wheel untilthe mower rotates about the second end by at least one hundred-eightydegrees.
 8. The method of claim 7, wherein driving the first drivenwheel comprises driving the first driven wheel until the mower rotatesabout the second end by at least five hundred-forty degrees.
 9. Themethod of claim 8, further comprising driving the second driven wheelsuch that the mower rotates about the first end by at least fivehundred-forty degrees.
 10. The method of claim 1, wherein the lengthexceeds thirty-six inches.
 11. The method of claim 10, wherein thelength exceeds seventy-two inches.
 12. The method of claim 1, whereinthe length is variable.
 13. The method of claim 12, wherein the lengthis variable between a first length of less than or equal to one hundredinches and a second length.
 14. The method of claim 13, wherein thesecond length is at least one hundred inches.
 15. The method of claim 1,further comprising steering the first driven wheel so that its directionof travel is approximately perpendicular to a cutting width axis of themower prior to the step of driving the first driven wheel.
 16. Themethod of claim 1, wherein the first driven wheel is steerable.
 17. Themethod of claim 16, wherein the second driven wheel is steerableindependently of the first driven wheel.
 18. The method of claim 4,further comprising steering the second driven wheel so that itsdirection of travel is approximately perpendicular to a cutting widthaxis of the mower prior to the step of driving the second driven wheel.19. A method for forming a pattern in grass, comprising: providing amower comprising: a plurality of connected cutting units having avariable cutting width, a first drive unit that is supported near afirst end of the mower, and a second drive unit that is supported near asecond end of the mower; and rotating the mower about the first end byat least one hundred eighty degrees by driving the second drive unit andthen rotating the mower about the second end by driving the first driveunit.
 20. A method for covering area, comprising: providing a framesystem comprising: a plurality of connected frames, the plurality havinga variable length, a first wheel that is supported near a first end ofthe plurality, and a second wheel that is supported near a second end ofthe plurality; causing the frame system to pivot about the first end bydriving at least the second wheel; and causing the frame system to pivotabout the second end by driving at least the first wheel.